Cytomegalovirus (CMV) infection is the most common infection that occurs after renal transplantation. Heretofore, only serum antibody has been used to assess immunity to CMV in prospective studies of transplant patients. Our objective in the studies in this proposal is to examine cell-mediated immunity to CMV in renal transplant recipients and to relate cell-mediated immunity to serum antibody, to CMV shedding immunosuppression, and illness due to CMV infection. We will do this serially determining humoral antibody and cell-mediated immunity to CMV when patients with end-stage renal disease present for renal transplantation. These tests will be determined frequently on these patients following transplantation. The patients' clinical status will also be followed closely so we can relate the immune status to CMV to their clinical status, especially that of febrile illnesses. We will determine serum antibody by complement-fixing method. Cell-mediated immunity will be determined by 3H-thymidine incorporation by peripheral blood T lymphocytes in response to CMV antigen. Responses to herpes simplex virus antigen, phytohemagglutinin, and concanavallin A will serve as controls. This study may demonstrate that tests of cell-mediated immunity to CMV provides more helpful information in determining who is at greatest risk for CMV infection in the eventual outcome of that infection.